He pulled out of the Open, which begins Aug. 28, because of an injured knee. He said he decided to undergo a “medical intervention” and sit out the rest of 2017. He did not provide any specifics about the injury or treatment.

“This was the only solution to make sure I will be able to compete at the top level for many more years,” Wawrinka said Friday in a statement through his agency.

He joins Novak Djokovic, the man he beat in last year’s final at Flushing Meadows, in calling it quits for this season because of an injury.

Wawrinka, 32, was clearly bothered by his left knee then, icing it during changeovers. He said after the defeat that the knee had been a problem on and off all season and that he needed to figure out what was wrong.

He finished with just one title this season and said he was looking toward to playing in 2018.

“I love this sport and I will work hard to get back to my top level and play many more years,” Wawrinka said.